Achilles Tendinosis

The tendon at the back of the ankle. The Achilles tendon joins the calf muscles to the back of the heel bone, and it takes the load each time you push off, walk uphill, run, jump or rise onto your toes. Ultrasound shows its thickness, its texture and, with Doppler, blood flow inside it; MRI also shows the bone and the small fluid sacs (bursae) around the attachment.

Tendinosis, tendinopathy, tendinitis. Tendinosis means the tendon’s structure has changed: its fibres are less orderly, and the tissue between them is altered. Tendinopathy is the general word for a painful tendon that is sensitive to load, the condition covered on the Achilles tendinopathy page. Tendinitis is the older word; it suggests inflammation alone, which is not the whole picture.

Mid-portion or insertional. Reports also say where the change is. Mid-portion (sometimes non-insertional or midsubstance) means the narrower middle part of the tendon, usually 2 to 6 cm above the heel bone. Insertional means where the tendon attaches to the heel bone, within about 2 cm of it (de Vos et al., 2021). The difference matters, because the two are loaded differently in rehabilitation.

The words around it. These are the terms you are likely to see with it on an ultrasound or MRI report.

It is common in tendons that do not hurt. Across 91 studies of people with no Achilles symptoms, the share with a tendon abnormality on imaging ranged from none to 80 percent. It was higher in people aged 40 or over, in people with a higher body mass index and in people who were physically active, and much of the remaining spread likely came from differences in how studies defined an abnormality and were designed (Docking et al., 2021).

It raises the odds of pain later, but most such tendons stayed painless. Across 16 studies that scanned painless tendons in athletes and then followed them, including 810 Achilles tendons, about 27 percent of abnormal-looking Achilles tendons became painful, and 92 percent of normal-looking ones stayed pain-free (Cushman et al., 2025).

Changes at the heel are common on the painless side too. In 71 people who had surgery for insertional pain in one heel, X-rays of the other, painless heel showed much the same bony bump and calcification at the attachment, only somewhat smaller on average, and none of the measurements told the painful heel from the painless one reliably (Nakajima, 2024).

It does not predict how you will recover. The Dutch guideline on Achilles tendinopathy advises against using imaging to predict the outcome, and asks clinicians to tell people who have had a scan that the findings do not predict how they will do (de Vos et al., 2021).

It often stays abnormal while you improve. In 23 people with long-standing mid-portion pain who did a 16-week heel-drop program, symptoms improved while the tendon’s structure on a detailed ultrasound measure did not change, and its structure at the start did not predict who improved (de Vos et al., 2012). In a larger trial the tendons did become thinner, with fewer vessels, as people improved (Beyer et al., 2015). Either way, the guideline advises against repeat scans to monitor treatment (de Vos et al., 2021).

It is not a diagnosis by itself. Achilles tendinopathy is diagnosed from four findings in the clinic: pain in one area of the tendon, pain with loading such as sport, local thickening (which can be missing early on) and tenderness when the tendon is pressed. When all four are present, the guideline advises that no imaging is needed; it suggests considering a scan, with ultrasound preferred, when the picture does not fit, the course is unexpected or surgery is being considered (de Vos et al., 2021).

Treatment builds how much load the tendon can take. Most of the trials below were in mid-portion pain and several are small, so the evidence is useful but not settled.

• Education, load advice and calf strengthening. The Dutch guideline advises starting with an explanation of the condition and its outlook, a temporary change to the activities that provoke it with a gradual build back up, and progressive calf strengthening for at least 12 weeks, in a form that suits the person (de Vos et al., 2021).
• Mid-portion and insertional pain are loaded differently. In one early study, the same 12-week heel-drop program gave a satisfactory result in 89 percent of mid-portion tendons but only 32 percent of insertional ones (Fahlström et al., 2003). Lowering the heel below the edge of a step bends the ankle up a long way, which presses an insertional tendon against the heel bone, so for insertional pain the exercises usually start on a flat floor, as the guideline suggests (de Vos et al., 2021). In a 2025 trial of 42 sport-active people with insertional pain, a program that limited how far the ankle bent up, left out calf stretching and used heel lifts gave better pain and function at 12 and 24 weeks than the same program without those limits; it tested the changes together, so it cannot say which one mattered (Pringels et al., 2025).
• Heavy slow strength or heel drops. In 58 people with long-standing mid-portion pain, heavy slow strength training and heel drops (eccentric exercise) both improved symptoms over 12 weeks and held at one year, with no clear difference between them, and people completed more of the heavy slow sessions (Beyer et al., 2015). That does not show the two are equal; it shows more than one program can help, so the choice can rest on what you prefer and will keep doing.
• Shockwave. Shockwave is one of the add-on options the Dutch guideline lists for a tendon that has not improved after about 3 months of education, load advice and exercise (de Vos et al., 2021). A 2026 review of nine trials found no clinically meaningful benefit over sham shockwave or no treatment, for mid-portion or insertional pain, on very low to moderate certainty evidence; two tendon ruptures were reported after focused shockwave, and the authors advised against routine use (Korakakis et al., 2026). The evidence is mixed. When I use it, it sits alongside exercise for a tendon that has not improved, not in place of it.
• Injections. In 100 adults with long-standing mid-portion pain, an ultrasound-guided steroid injection added to exercise improved symptoms more than a placebo injection at six months, with no severe side effects and no worsening over two years (Johannsen et al., 2022). The injections, up to three, went around the tendon rather than into it, and everyone avoided running and jumping for three months, so the result does not carry over to injections into the tendon or an earlier return to impact. In 192 adults, high-volume injections with or without steroid did no better than a sham injection at a year, alongside the same exercise program; the steroid version helped more at six weeks but did worse than the version without steroid at 26 weeks (Malliaras et al., 2026). The guideline advises caution with steroid injections (de Vos et al., 2021). Any injection is a physician’s decision, and loading stays at the centre of the plan.
• Surgery. The guideline advises considering surgery only after at least six months of active treatment has not helped, weighing it against continued non-surgical care and its possible complications (de Vos et al., 2021).
• What that means for your report. Tendinosis or a bump at the heel on a scan is not on its own a reason for an injection or an operation. A loading program comes first; a surgical opinion, through your family doctor, is for a tendon that still limits you after a fair course.

• It describes a full-thickness or complete tear, a rupture, or a gap between the tendon ends. That is a different problem from tendinosis: if a doctor has not already seen it, get a same-day medical assessment and avoid walking on it until it has been checked. In the clinic, a calf squeeze that does not make the foot point down (a positive Thompson test) raises the same concern.
• It describes a large or high-grade partial tear. That is worth your doctor’s opinion before heavy loading.
• The middle of the tendon is thickened and you know or suspect an inherited high cholesterol: very high cholesterol of your own, or a parent, brother, sister or child who had heart disease before 60. A thickened tendon can then be a cholesterol deposit (a xanthoma), and the guideline suggests considering a medical referral (de Vos et al., 2021); your family doctor is the place to start.
• It mentions enthesitis, or you have psoriasis or long-standing low back pain that began before the age of 45. Pain where a tendon attaches can come from an inflammatory arthritis (spondyloarthritis), and with insertional pain the guideline suggests considering a rheumatology referral when that is known or suspected (de Vos et al., 2021).
• You are under 18. Achilles symptoms at that age usually come from the growth area of the heel bone rather than the tendon (de Vos et al., 2021); the Sever’s disease page covers it.
• It flags something in the bone or elsewhere that is not about the tendon. Ask the doctor who ordered the scan to go through it with you.
• The pain has not improved after about 3 months of education, load advice and well-run exercise, or it changes in a way that does not fit. The guideline suggests discussing add-on treatment then, considering further imaging for an unexpected course, and a referral to a sports medicine physician or orthopaedic surgeon if the diagnosis stays uncertain (de Vos et al., 2021).

I start with where it hurts and what brings it on. Pain in the narrow middle of the tendon, or right where it meets the heel bone, that is stiff first thing in the morning and sore with walking uphill, running, hopping or rising onto the toes points to the tendon. Pain made much worse by the back of a shoe pressing on the heel points more to the bursa or the bump of bone. I also ask about new antibiotics, cholesterol, psoriasis and back stiffness, because each changes who else should be involved.

On examination I press along the tendon and around the heel, compare the two sides, test calf strength with single-leg heel raises and watch how you walk, hop and push off. A calf squeeze that does not make the foot point down means a possible rupture, which needs a same-day medical assessment. I read the report alongside all of that, giving more weight to how the tendon behaves than to how it looks. I cannot order imaging; when further imaging would change the plan, I flag it and refer you.

The plan builds load in stages: holds when the tendon is irritable, heavy slow calf work or heel drops for mid-portion pain, raises on a flat floor for insertional pain, then hopping and running before full sport. Running is often cut back rather than stopped, and how the tendon feels the next morning guides each step. The Achilles tendinopathy page sets out the stages in detail.